ICD-10 Coding for Subcutaneous Periumbilical Cyst
The most appropriate ICD-10 code for a subcutaneous cyst in the periumbilical region identified on ultrasound is L72.0 (Epidermal cyst) or L72.9 (Follicular cyst of skin and subcutaneous tissue, unspecified), depending on the specific histologic characteristics if known.
Primary Code Selection
L72.0 (Epidermal cyst) is the most specific code when the ultrasound characteristics suggest an epidermoid/epidermal inclusion cyst, which appears as a well-circumscribed, avascular mass in subcutaneous tissue with posterior acoustic enhancement 1
L72.9 (Follicular cyst of skin and subcutaneous tissue, unspecified) serves as an appropriate alternative when the exact cyst type cannot be determined from imaging alone 1
Anatomic Location Coding
The periumbilical location is captured by the primary cyst code (L72.x series), as these codes apply to cysts of skin and subcutaneous tissue regardless of body site 1
No additional anatomic site code is required, as the umbilical/periumbilical region falls under the general "skin and subcutaneous tissue" category covered by L72.x codes
Alternative Diagnoses to Exclude
Before finalizing the L72.x code, ensure the ultrasound findings do not suggest:
Urachal remnant cyst - would require Q64.4 (Malformation of urachus), which presents as a midline infraumbilical mass rather than subcutaneous periumbilical 2
Umbilical pilonidal sinus - would use L05.91 (Pilonidal cyst without abscess), though this is extremely rare in the umbilical region and typically shows a sinus tract on imaging 2
Hydatid cyst - would require B67.99 (Echinococcosis, unspecified, other sites), but this is exceptionally rare in subcutaneous tissue without liver/lung involvement and would show characteristic multivesicular appearance 3
Documentation Requirements
To support accurate coding, ensure the ultrasound report specifies:
Exact location: "subcutaneous tissue of periumbilical region" rather than intra-abdominal 1
Cyst characteristics: round/oval, well-circumscribed, avascular on color Doppler, with or without posterior acoustic enhancement 1
Size measurements: document maximum diameter in any plane 1
Critical Coding Pitfall
Do not use codes from the R19.0x series (Intra-abdominal and pelvic swelling, mass and lump), as these are symptom codes inappropriate when a specific diagnosis (subcutaneous cyst) has been established by imaging 1. The subcutaneous location definitively excludes intra-abdominal pathology codes.